Geant4 simulations of measurement of energy spectra of reflected ions generated by nanosecond-laser-drive non-relativistic collisionless electrostatic shocks
-
摘要: 间接驱动惯性约束聚变真空或者近真空黑腔实验中，纳秒激光烧蚀产生的腔壁等离子体可以在靶丸烧蚀等离子体（或低密度填充气体）中驱动无碰撞静电冲击波，冲击波电场会以二倍冲击波速度反射离子。为了测量纳秒激光驱动非相对论无碰撞静电冲击波产生的10 keV量级的反射离子能谱，设计了低能汤姆逊离子谱仪。利用Geant4建模，对离子测量过程进行了全过程蒙特卡罗模拟，用以评估靶室残余气体和喷气气体对低能离子测量的影响。模拟结果显示，靶室残余气体会造成10 keV量级D离子信号在谱仪电场和磁场方向展宽。电场方向的展宽会增加不同荷质比离子谱线发生交叠的风险，而磁场方向的展宽会导致离子能谱展宽。喷气气体会造成离子信号向低能区移动并拖尾，导致测量的离子谱偏离真实的反射离子能谱。
-
关键词:
- 非相对论无碰撞静电冲击波 /
- 反射离子能谱 /
- 蒙特卡洛模拟
Abstract: In indirect-drive inertial confinement fusion experiments with vacuum or low-gas-fill hohlraums, collisionless electrostatic shocks can be launched in the hohlraum wall/alblator (or the low-density fill-gas) interpenetration region, which reflect ions at twice the shock velocity. A low-energy Thomson ion spectrometer was designed to measure the energy spectra of the reflected ions on the order of 10 keV generated by nanosecond-laser-driven non-relativistic collisionless electrostatic shocks. Monte Carlo simulations of ion measurement were carried out with Geant4 modeling to evaluate the influence of residual gas in the vacuum chamber and gas jet on the measurement of the low-energy ions. Simulation results show that the residual gas in the vacuum chamber causes the signal of D ions on the order of 10 keV to broaden in both the electric and magnetic deflection of the spectrometer. The broadening of the electric deflection will increase the risk of overlapping of ion spectral lines of different charge-to-mass ratios, while the broadening of the magnetic deflection will lead to the broadening of the energy spectra of the ions. The gas jet causes the ion signal to move and tail into the lower energy region, causing the measured ion spectra to deviate from the actual energy spectra of the reflected ions. -
图 1 （a）喷气靶示意图，（b）低能汤姆逊离子谱仪结构及D离子运动轨迹，（c）D离子能量与偏转距离的关系，（d）谱仪的Geant4模型示意图
Figure 1. (a)Schematic diagram of gas-jet target,(b)structure of the low-energy Thomson ion spectrometer and trajectories of D ions, (c) the relationship between the energy of D ion and the deflection distance, (d) schematic diagram of Geant4 model of the spectrometer
图 2 不同能量的单能D离子源在IP成像板处的流强信号
Figure 2. Current intensities of monoenergetic D ions at the positions of image plates
图 3 靶室真空度1×10−2 Pa情况下信号在电场和磁场方向的分布
Figure 3. Distributions of the signals in the electric and magnetic deflection when the air pressure of the vacuum target chamber is 1×10−2 Pa
图 4 信号在电场和磁场方向的半高全宽
Figure 4. Full widths at half maximum of the signals in the electric and magnetic deflection
图 5 （a）考虑喷气气体后D离子在IP成像板处的流强信号，（b）考虑喷气气体前（黑线）后（红线）信号在磁场方向的分布
Figure 5. (a) Current intensities of D ions at the positions of image plates after considering the gas jet, (b) the distributions of the signals in the magnetic deflection before (black line) and after (red line) considering the gas jet
-
[1] Hurricane O A, Callahan D A, Casey D T, et al. Fuel gain exceeding unity in an inertially confined fusion implosion[J]. Nature, 2014, 506(7488): 343-348. doi: 10.1038/nature13008 [2] Zylstra A B, Hurricane O A, Callahan D A, et al. Burning plasma achieved in inertial fusion[J]. Nature, 2022, 601(7894): 542-548. doi: 10.1038/s41586-021-04281-w [3] Kritcher A L, Young C V, Robey H F, et al. Design of inertial fusion implosions reaching the burning plasma regime[J]. Nature Physics, 2022, 18(3): 251-258. doi: 10.1038/s41567-021-01485-9 [4] Abu-Shawareb H, Acree R, Adams P, et al. Lawson criterion for ignition exceeded in an inertial fusion experiment[J]. Physical Review Letters, 2022, 129: 075001. doi: 10.1103/PhysRevLett.129.075001 [5] Zylstra A B, Kritcher A L, Hurricane O A, et al. Experimental achievement and signatures of ignition at the National Ignition Facility[J]. Physical Review E, 2022, 106: 025202. doi: 10.1103/PhysRevE.106.025202 [6] Kritcher A L, Zylstra A B, Callahan D A, et al. Design of an inertial fusion experiment exceeding the Lawson criterion for ignition[J]. Physical Review E, 2022, 106: 025201. doi: 10.1103/PhysRevE.106.025201 [7] Amendt P, Landen O L, Robey H F, et al. Plasma barodiffusion in inertial-confinement-fusion implosions: application to observed yield anomalies in thermonuclear fuel mixtures[J]. Physical Review Letters, 2010, 105: 115005. doi: 10.1103/PhysRevLett.105.115005 [8] Rinderknecht H G, Sio H, Li C K, et al. First observations of nonhydrodynamic mix at the fuel-shell interface in shock-driven inertial confinement implosions[J]. Physical Review Letters, 2014, 112: 135001. doi: 10.1103/PhysRevLett.112.135001 [9] Rosenberg M J, Rinderknecht H G, Hoffman N M, et al. Exploration of the transition from the hydrodynamiclike to the strongly kinetic regime in shock-driven implosions[J]. Physical Review Letters, 2014, 112: 185001. doi: 10.1103/PhysRevLett.112.185001 [10] Le Pape S, Divol L, Huser G, et al. Plasma collision in a gas atmosphere[J]. Physical Review Letters, 2020, 124: 025003. doi: 10.1103/PhysRevLett.124.025003 [11] Rygg J R, Séguin F H, Li C K, et al. Proton radiography of inertial fusion implosions[J]. Science, 2008, 319(5867): 1223-1225. doi: 10.1126/science.1152640 [12] Li C K, Séguin F H, Frenje J A, et al. Charged-particle probing of X-ray-driven inertial-fusion implosions[J]. Science, 2010, 327(5970): 1231-1235. doi: 10.1126/science.1185747 [13] Li C K, Séguin F H, Frenje J A, et al. Impeding hohlraum plasma stagnation in inertial-confinement fusion[J]. Physical Review Letters, 2012, 108: 025001. doi: 10.1103/PhysRevLett.108.025001 [14] Hua R, Kim J, Sherlock M, et al. Self-generated magnetic and electric fields at a Mach-6 shock front in a low density helium gas by dual-angle proton radiography[J]. Physical Review Letters, 2019, 123: 215001. doi: 10.1103/PhysRevLett.123.215001 [15] Jones O S, Cerjan C J, Marinak M M, et al. A high-resolution integrated model of the National Ignition Campaign cryogenic layered experiments[J]. Physics of Plasmas, 2012, 19: 056315. doi: 10.1063/1.4718595 [16] Hopkins L F B, Meezan N B, Le Pape S, et al. First high-convergence cryogenic implosion in a near-vacuum hohlraum[J]. Physical Review Letters, 2015, 114: 175001. doi: 10.1103/PhysRevLett.114.175001 [17] Hopkins L F B, Le Pape S, Divol L, et al. Near-vacuum hohlraums for driving fusion implosions with high density carbon ablators[J]. Physics of Plasmas, 2015, 22: 056318. doi: 10.1063/1.4921151 [18] Rinderknecht H G, Amendt P A, Wilks S C, et al. Kinetic physics in ICF: present understanding and future directions[J]. Plasma Physics and Controlled Fusion, 2018, 60: 064001. doi: 10.1088/1361-6587/aab79f [19] Shan L Q, Cai H B, Zhang W S, et al. Experimental evidence of kinetic effects in indirect-drive inertial confinement fusion hohlraums[J]. Physical Review Letters, 2018, 120: 195001. doi: 10.1103/PhysRevLett.120.195001 [20] Cai H B, Shan L Q, Yuan Z Q, et al. Study of the kinetic effects in indirect-drive inertial confinement fusion hohlraums[J]. High Energy Density Physics, 2020, 36: 100756. doi: 10.1016/j.hedp.2020.100756 [21] 单连强, 吴凤娟, 袁宗强, 等. 激光惯性约束聚变动理学效应研究进展[J]. 强激光与粒子束, 2021, 33:012004 doi: 10.11884/HPLPB202133.200235Shan Lianqiang, Wu Fengjuan, Yuan Zongqiang, et al. Research progress of kinetic effects in laser inertial confinement fusion[J]. High Power Laser and Particle Beams, 2021, 33: 012004 doi: 10.11884/HPLPB202133.200235 [22] 蔡洪波, 张文帅, 杜报, 等. 惯性约束聚变黑腔内等离子体界面处的动理学效应及其影响[J]. 强激光与粒子束, 2020, 32:092007Cai Hongbo, Zhang Wenshuai, Du Bao, et al. Characteristic and impact of kinetic effects at interfaces of inertial confinement fusion hohlraums[J]. High Power Laser and Particle Beams, 2020, 32: 092007 [23] Wei M S, Mangles S P D, Najmudin Z, et al. Ion acceleration by collisionless shocks in high-intensity-laser-underdense-plasma interaction[J]. Physical Review Letters, 2004, 93: 155003. doi: 10.1103/PhysRevLett.93.155003 [24] Zhang H, Shen B F, Wang W P, et al. Collisionless shock acceleration of high-flux quasimonoenergetic proton beams driven by circularly polarized laser pulses[J]. Physical Review Letters, 2017, 119: 164801. doi: 10.1103/PhysRevLett.119.164801 [25] He S K, Jiao J L, Deng Z G, et al. Generation of ultrahigh-velocity collisionless electrostatic shocks using an ultra-intense laser pulse interacting with foil-gas target[J]. Chinese Physics Letters, 2019, 36: 105201. doi: 10.1088/0256-307X/36/10/105201 [26] Schmid K, Veisz L. Supersonic gas jets for laser-plasma experiments[J]. Review of Scientific Instruments, 2012, 83: 053304. doi: 10.1063/1.4719915 [27] Fryxell B, Olson K, Ricker P, et al. FLASH: an adaptive mesh hydrodynamics code for modeling astrophysical thermonuclear flashes[J]. The Astrophysical Journal Supplement Series, 2000, 131(1): 273-334. doi: 10.1086/317361 [28] Balogh A, Treumann R A. Physics of collisionless shocks[M]. New York: Springer, 2013: 1-500. -
下载:
点击查看大图
图(7)
计量
- 文章访问数: 508
- HTML全文浏览量: 204
- PDF下载量: 81
- 被引次数: 0
